13 ms·

I don't think that's new either, I remember doing that in 2015, to demonstrate an issue.

• tyingq 8y ago
  There's this, from 2015: https://news.ycombinator.com/item?id=8555079 https://news.ycombinator.com/item?id=8555079 And colliding SHA-1 in pdf form in 2017: https://news.ycombinator.com/item?id=13723892 https://news.ycombinator.com/item?id=13723892 Not saying you didn't, but I'm unable to find any earlier reference to making 2 arbitrary, existing pdf files collide with MD5.
  • diminoten 8y ago
    I must have done the first link's thing. But once you can do that, this isn't new. Assuming you can append garbage on a PDF, it's the same solution. Admittedly I know how easy it is to say, "That's obvious!" in hindsight, but... isn't it?!
    • tyingq 8y ago
      It is more complex than just writing past the end of file with arbitrary garbage, as you can with a jpg. He explains the method here: https://github.com/corkami/pocs/blob/master/collisions/README.md#pdf https://github.com/corkami/pocs/blob/master/collisions/READM...
    • krageon 8y ago
      The fact that he produced something easy to see helps cement in the mind of more people exactly how possible it is. It's a benefit not in the sense that it was impossible before, but rather a benefit in the sense that more people will really believe that it is possible.
      • diminoten 8y ago
        I didn't say it wasn't a benefit, I said there is no new innovation here. I was kind of wrong, but only insofar as it uses a different way to embed arbitrary garbage in a PDF instead of directly at the end. The concept is still the same (as it has to be).